Subgroups
An important factor in preparing for CQI charting is determining if you will measure every product of the process, such as timing every patient’s wait time, or if you will use subgroups. Subgroups are a sample of data from the total possible data. Subgroups are used when it is impractical or too expensive to collect data on every single product or service in the process. Decisions to use subgroups or not needs to be carefully thought out to ensure they accurately represent the data.
Subgroups need to be homogenous within them so that special causes can be recognized, so problem areas stand out from the normal variation in the subgroup. For example, if you are in charge of analyzing processes in a number of affiliated hospitals, a separate group should represent each hospital, since each hospital has different processes for doing the same tasks. Each hospital subgroup should probably be broken down even further, for example by work shifts.
